1. Field of the Invention
The invention relates to a variable focusing flashlight, more particularly to a variable focusing flashlight which has a simple construction and an improved power supply switch configuration.
2. Description of the Related Art
Variable focusing flashlights are known in the art. Referring to FIGS. 1, 2 and 3, a conventional variable focusing flashlight disclosed in U.S. Pat. No. 4,942,505 is shown to comprise a metal barrel (11) which is adapted to receive dry cell batteries (10) therein. The barrel (11) has a first open end which is formed with an inwardly projecting annular lip (111). A lower insulator receptacle (12) is provided inside the barrel (11) adjacent to the first open end of the same. A pair of conductors (121, 122) are mounted in the receptacle (12). One end of the conductor (121) is bent so as to contact the lip (111). One end of the conductor (122) extends through a closed bottom of the receptacle (12) so as to contact the positive terminal of the dry cell batteries (10). The receptacle (12) is further formed with a pair of arcuate recesses (120). An upper insulator receptacle (13) is formed with a pair of holes (131) which are aligned with the conductors (121, 122). A lamp bulb (14) is provided with lamp electrodes (141) which pass through the holes (131) of the receptacle (13) and which connect electrically with the conductors (121, 122). The receptacle (13) is provided with arcuate extensions (132) which are received in the arcuate recesses (120) of the receptacle (12) The receptacles (12, 13) are disposed on two sides of the lip (111) of the barrel (11) when installed. A tail cap (143) threadedly encloses a second open end of the barrel (11). The tail cap (143) is provided with a helical compression spring (142) which urges the dry cell batteries (10) toward the conductor (122). A head assembly (15) has a substantially parabolic reflector (151) and threadedly engages the first open end of the barrel (11). The parabolic reflector (151) has an open tail end which is in contact with the receptacle (13). The head assembly (15) is rotated relative to the barrel (11) so as to vary the light output of the flashlight and so as to make or break electrical connection between the dry cell batteries (10) and the lamp bulb (14).
Rotation of the head assembly (15) in a direction toward the barrel (11) causes the parabolic reflector (151) to push the receptacle (13) toward the dry cell batteries (10). The conductor (121) does not contact the lip (111) at this time, thereby breaking electrical connection between the lamp bulb (14) and the dry cell batteries (10). Rotation of the head assembly (15) in a direction away from the barrel (11) causes the spring (142) to expand, thereby resulting in electrical contact between the conductor (121) and the lip (111) to cause the operation of the lamp bulb (14). Further rotation of the head assembly (15) in this direction varies the position of the parabolic reflector (151) relative to the lamp bulb (14), thereby varying the dispersion of the light output of the flashlight.
The following are some of the drawbacks of the above-disclosed variable focusing flashlight:
1. The flashlight is turned off by breaking electrical contact between the conductor (121) and the lip (111), thereby disconnecting the lamp bulb (14) from the negative terminal of the dry cell batteries (10).
2. The flashlight is relatively inconvenient to assemble. Note that the receptacle (12) has to be inserted from the second open end of the barrel (11) before the receptacle (13) can be assembled thereto because of the presence of the lip (111). Assembly of the receptacles (12, 13) is therefore difficult to conduct, especially if the barrel (11) is relatively long.
3. The receptacle (13) moves the receptacle (12) by a relatively small distance so as to turn on or turn off the flashlight. The conductor (121) should therefore be precisely bent so as to ensure accurate power supply switching. Precise bending of the conductor (121) is difficult to achieve. If the conductor (121) is improperly bent, the power supply switch of the flashlight is disabled, thereby maintaining the flashlight in an on or off state.
4. The receptacles (12, 13) must be properly matched so as to achieve tight connection between the same. Improper matching of the receptacles (12, 13) may result in the untimely disengagement of the receptacles (12, 13) when replacement of the lamp bulb (14) or the dry cell batteries (10) is being effected.
5. Constant contact between the conductor (122) and the dry cell batteries (10) can cause wearing of the former, thereby reducing the useful life of the flashlight.
6. Machining of the lip is difficult to achieve. The power supply switch of the flashlight is affected if the lip (111) is relatively thick. The lip (111), however, easily breaks if the lip (111) is relatively thin.